In recent years alternative network telephony, using a network other than the public switched telephone network (PSTN) to enable two or more parties to carry on a conversation in real time, has become increasingly popular. The advent of high-speed access to networks, such as the Internet, has further fueled this trend. Telephone functionality has been provided using personal computers (PC's) or computer workstations connected via the Internet and/or other networks, often through high-speed connections such as cable modems or digital subscriber line (DSL) connections. Telephone functionality has also been provided via cable television networks through television set top boxes, for example.
In many cases, a packet switched network protocol, such as the Internet protocol (IP) is used to provide alternative network telephony (e.g., IP telephony). Under such a protocol, the analog audio signal generated by a speaking call participant is digitized and sent via the alternative network from the sending station to the receiving station(s) in one or more data packets conforming to the applicable protocol. At the receiving end, the data typically is reassembled, if necessary, and converted back to an analog audio signal. The data is then typically delivered to the recipient via an audio output device, such as one or more speakers, a headset, or a telephone handset or other output device.
It would be desirable for cable television service providers, providers of interactive television services and/or equipment, and/or other providers or potential providers of alternative network telephony equipment and services to have a way to compete effectively with more traditional providers of long distance and/or local telephone service. Such competition may bring lower prices, better and expanded service, and more choice to consumers.
One way that alternative network telephony might be used to enhance service is by providing the functionality of multiple telephone extensions without requiring multiple lines connected to the public switched telephone network (PSTN). Complex switches, such as private branch exchange (PBX) switches, have been provided to route calls coming in on a single PSTN line to two or more internal lines. However, such switches typically are expensive to acquire and install, making their use by consumers and small businesses impractical in many cases.
Therefore, there is a need for a way to use alternative network telephony to provide PBX-type functionality, specifically the ability to make and receive calls on multiple internal lines while having only a single PSTN line.